In a communications system, a transmitter may upconvert a baseband signal into a radio-frequency (RF) signal by mixing the baseband signal with a local oscillator (LO) signal using a mixer. A receiver may receive the RF signal from the transmitter and downconvert the received signal from RF to baseband, also by mixing the RF signal with an LO signal using a mixer. In both the transmitter and receiver, an LO buffer may be provided to buffer an LO signal before providing it to the mixer.
The optimal sizes for the mixer and the LO buffer depend on the requirements of the transmitter or receiver. For example, in a transmitter, the sizes of the mixer and LO buffer may depend on the total transmit power required from the transmitter. See, e.g., U.S. patent application Ser. No. 11/855,997, earlier referenced herein. In a receiver, larger mixer size tends to improve receiver linearity, while a smaller mixer size reduces power consumption. Employing a larger mixer size usually mandates a correspondingly larger LO buffer, as the size of the mixer directly determines the load on the LO buffer.
In conventional transmitters and receivers, the sizes of the LO buffer and mixer are fixed. It would be desirable to dynamically adjust the size of the LO buffer and/or mixers depending on the requirements of the transmitter or receiver.